The present invention relates generally to data communications networks and more particularly relates to a system for probing selected Switched Virtual Circuits (SVCs) in a connection oriented network such as an Asynchronous Transfer Mode (ATM) network.
Currently, there is a growing trend to make Asynchronous Transfer Mode (ATM) networking technology the base of future global communications. ATM has already been adopted as a standard for broadband communications by the International Telecommunications Union (ITU) and by the ATM Forum, a networking industry consortium.
ATM originated as a telecommunication concept defined by the Comite Consulatif International Telegraphique et Telephonique (CCITT), now known as the ITU, and the American National Standards Institute (ANSI) for carrying user traffic on any User to Network Interface (UNI) and to facilitate multimedia networking between high speed devices at multi-megabit data rates. ATM is a method for transferring network traffic, including voice, video and data, at high speed. Using this connection oriented switched networking technology centered around a switch, a great number of virtual connections can be supported by multiple applications through the same physical connection. The switching technology enables bandwidth to be dedicated for each application, overcoming the problems that exist in a shared media networking technology, like Ethernet, Token Ring and Fiber Distributed Data Interface (FDDI). ATM allows different types of physical layer technology to share the same higher layerxe2x80x94the ATM layer.
ATM uses very short, fixed length packets called cells. The first five bytes, called the header, of each cell contain the information necessary to deliver the cell to its destination. The cell header also provides the network with the ability to implement congestion control and traffic management mechanisms. The fixed length cells offer smaller and more predictable switching delays as cell switching is less complex than variable length packet switching and can be accomplished in hardware for many cells in parallel. The cell format also allows for multi-protocol transmissions. Since ATM is protocol transparent, the various protocols can be transported at the same time. With ATM, phone, fax, video, data and other information can be transported simultaneously.
ATM is a connection oriented transport service. To access the ATM network, a station requests a virtual circuit between itself and other end stations, using the signaling protocol to the ATM switch. ATM provides the User Network Interface (UNI) which is typically used to interconnect an ATM user with an ATM switch that is managed as part of the same network.
The current standard solution for routing in a private ATM network is described in Private Network Node Interface (PNNI) Phase 0 and Phase 1 specifications published by ATM Forum. The previous Phase 0 draft specification is referred to as Interim Inter-Switch Signaling Protocol (IISP). The goal of the PNNI specifications is to provide customers of ATM network equipment some level of multi-vendor interoperability.
Networks that are connection oriented typically have two stages for connecting network users from point to point. The first stage in the establishment of the colnection utilizes some form of signaling mechanism and in the second stage, data is transferred via the connection established in the first stage.
An example of such as connection oriented network is an ATM network. ATM networks utilize a signaling protocol that is derived from the Q.93B standard to provide network users a service for establishing a connection to another network user. This connection is termed a Switched Virtual Connection (SVC) and, once created, is used as the data path between the users that have been connected.
The connection originator uses the signaling protocol to convey the service details it is requesting the network to provide, e.g., destination address (i.e. the called address), calls of service, traffic descriptor, protocol which is to be used by the virtual connection, network transit, etc. In addition, the originator provides information about itself, in particular, its own address (i.e. the calling address).
Once the network receives the request from the originator user, it attempts to find a route to the destination that has sufficient resources to fulfill the specific characteristic requirements of the request as provided by the originating user. If the network finds a satisfactory route with the necessary resources to establish the connection, and if the called user also has sufficient resources to establish the connection, the connection is then established. Once the route is established, data can flow between source and destination over the connection.
Such a network may carry another type of connection known as a Permanent Virtual Circuit (PVC) which are typically established under manual management control. The service provided by PVCs and SVCs are the same, with the difference being their method of establishment.
In the course of network operations, SVCs may be constantly created and torn down. SVC connections may be created very quickly and last for a relatively short lifetime duration, i.e., hundreds, of milliseconds, seconds, etc., before being removed. In the event a network manager desires to capture SVC traffic for purposes of analysis, the specific SVC must first be identified, and data somehow routed to the management station. Normally, this must be done manually, without effecting the original data path, and without any synchronization in time with the establishment of the SVC and the data being transferred over it. Although it is possible for a network manager to capture data from the SVC, the establishment of the capture mechanism may take many tens of minutes depending on the type and sophistication of the management tools available. During this time the SVC may have already been established and removed making its capture impossible using current techniques.
It would therefore be desirable to have a capture mechanism that can be utilized by a network management station and that is capable of capturing very, short lived SVCs without interfering or effecting the flow of data over the SVC from calling to called users.
The present invention is a system for probing one or more SVCs that enables a network management station to setup a probe event in advance before a SVC is created. Upon the creation of the SVC, the data is captured and sent to the network management station without any further intervention required. Note that the system of the present invention is applicable to any connection-oriented network that utilizes signaling to establish connections between network users.
The invention establishes a SVC probe in two stages. In the first stage, a SVC originator is configured with a probing IE containing parameters to be included in the SETUP request message when SVCs are established. The probing IE is generated by the network management station and sent to the SVC originator using standard SNMP techniques. A unique identifier is included as one of the parameters in the probing IE. It is used by the probing switch to detect a SVC that is to be probed.
A PVC is established to the switch containing one or more SVCs that are to be probed. A probing port is configured on the switch and a range of VPI/VCIs are assigned to the port. The same unique identifier is configured in the switch to be probed.
In operation, the switches along the path, attempt to find a match between the unique identifier included in the SETUP request message and that previously configured by the management station. If a match is found, a multicast connection is configured in the switch and traffic from the SVC originator is directed toward both the destination and the probing port. Likewise, traffic from the destination is directed toward both the SVC originator and the probing port. In this fashion, the SVC traffic can be analyzed using diagnostic tools located remotely anywhere in the network.
The probing system of the present invention can also be used to probe multiple SVCs from the same or different SVC originators. In addition, multiple network management stations can coexist with each setting up multiple probing ports on different switches. In this case, each switch maintains a table of probe identifiers and maps each to a different probing port with each probing port corresponding to a different PVC.
There is provided in accordance with the present invention, in a connection oriented network capable of establishing Switched Virtual Circuits (SVCs) and Permanent Virtual Circuits (PVCs), a method of probing one or more SVCs established by a SVC originator comprising the steps of configuring, from a network management station, a SVC originator with a first set of probe parameters comprising a global probing ID, configuring, from the network management station, a probing switch with a second set of probing parameters comprising the global probing ID, establishing, from the network management station, a PVC to a designated probing port on the probing switch, incorporating the first set of probing parameters in a setup request message at the time the SVC originator established a SVC to a destination and copying bidirectional traffic between the SVC originator and the destination to the network management station via the PVC.
The first set of probing parameters comprises initial probing VPI/VCI and maximum probing VPI/VCI parameters, whereby upon each successive SVC established, the SVC originator increments the VCI up to the maximum. The first set of probing parameters comprises a probing enable/disable parameter operative to turn probing off in the SVC originator. The setup message comprises a probing Information Element (IE) comprising the global probing ID, initial probing VPI/VCI, maximum probing VPI/VCI and probing enable/disable parameters.
The SVC originator is configured utilizing Simple Network Management Protocol (SNMP) messages generated by the network management station. The probing switch is configured utilizing Simple Network Management Protocol (SNMP) messages generated by the network management station.
The step of copying comprises the step of establishing a multicast connection from a port receiving traffic from the SVC originator to a port sending traffic toward the destination port and to the probing port and the step of copying comprises the step of establishing a multicast connection from a port receiving traffic from the destination to a port sending traffic toward the SVC originator and to the probing port.
The method further includes the step of maintaining a table of global probing IDs when a plurality of SVC originators are present in the network. The method further includes the step of ceasing, on the SVC originator, to incorporate the first set of probing parameters in the setup message when a maximum probing VPI/VCI has been reached.
The method further includes the step of assigning, in the probing switch, odd VPI/VCI numbers for the probing port to traffic flowing in a first direction and even VPI/VCI numbers for traffic flowing in a second direction opposite that of the first direction. The method further includes the step of assigning, in the probing switch, even VPI/VCI numbers for the probing port to traffic from the SVC originator.